We have been happily running FudForum 2.6.x at www.sputnik.com for a few years. It was integrated into our site's page wrapper and used themes to make it fit in with the rest of the site.

Recently we installed WordPress 2.01, adding a blog to our site.

Shortly thereafter, we noticed that new posts result in a system error. (Responses to existing posts seem to work.) Coincidentally, some of the sidebars in affected pages called posts from WordPress. We thought there might be some "interference" and removed the WordPress references from the sidebars on Forums pages. Unfortunately, that didn't fix things.

We then upgraded to the latest WordPress - 2.7.4 - and voila, you could post again.

However, once we re-applied our themes, the system error cropped up again, making it impossible to add new posts.

The system error on the post page is caused by missing parameters being passed to the page. For example if neither $th_id or $frm_id parameters are supplied. Is it possible that Wordpress is somehow clearing out those values?